In many applications, it is highly desirable to minimize the number of fasteners that extend through a housing. This is particularly true where sealing is required since the fluid to be retained within the housing, which is usually under pressure, can leak at such locations. Nevertheless, it is generally recognized as essentially impossible to completely eliminate this potential source of leakage, e.g., bolts extending through housings.
For instance, the aforementioned problem is known to exist in generators. This is particularly true of internal pressurized gas filled and spray oil cooled generators for use in high ambient temperature environments on the order of 700.degree.-800.degree. F. Such generators are commonly utilized for electrical power in aircraft and the like.
Typically, such generators utilize nitrogen at a pressure on the order of 7 lbs. per square inch and utilize oil for cooling at a pressure on the order of 250 lbs. per square inch. With the ambient temperature generally in the range of between approximately 700.degree.-800.degree. F., the temperature internally of the generator housing is on the order of approximately 250.degree. F. Unfortunately, conventional seals that are utilized under the head of a bolt are not capable of withstanding a temperature above about 500.degree. F. and are therefore not suited for use in environments having such high ambient temperature.
Nevertheless, it would be highly desirable to utilize seals of conventional materials in order to be able to control expenses. These seeming contradictions are further confused by the fact that the seals should be readily accessible from the exterior of the generator housing in order to permit economical periodic maintenance to be performed, e.g., replacement of seals without the need to disassemble the generator. Accordingly, the present invention is directed to overcoming the above stated problems and accomplishing the stated objects.